1. Technical Field
The present invention is related to a fall protection device, and more particularly related to a fall protection device which is adapted for use in hoisting operation workplace.
2. Description of Related Art
Workers usually wear a fall protection device including a safety belt when they work in elevated workplaces; the safety belt is attached to the worker and the fall protection device is secured to a support. If the worker falls accidentally, the fall protection device and the safety belt are able to prevent the worker from continuing to fall so as to ensure the safety of the worker.
As shown in FIG. 1, a conventional fall protection device 1 includes a housing 10, a frame 12 disposed in the housing 10, a rotation unit 14, a safety belt 16, a rewinding unit 18, a braking plate 20 and two braking blocks 22. Wherein, the housing 10 is constituted by two housing parts 102 which are joined to each other. The frame 12 includes a first lateral plate 122 and a second lateral plate 124 which face each other. The rotation unit 14 is rotatably disposed between the first lateral plate 122 and the second lateral plate 124, wherein a stopping block 122a is formed on the first lateral plate 122. The safety belt 16 is wound around the rotation unit 14. The rewinding unit 18 is disposed at an exterior side of the second lateral plate 124 which includes a spiral spring 182 connected to the rotation unit 14, and is adapted to provide a force to rewind the safety belt 16. The braking plate 20 is disposed at an exterior side of the first lateral plate 122, and is engaged with the rotation unit 14 so as to be rotated with the rotation unit 14. The braking plate 20 has an exterior surface 202 which is opposite to the first lateral plate 122. The braking block 22 is disposed on the exterior surface 202 of the braking plate 20 and is pivotally connected to a pivot 202a formed on the exterior surface 202 wherein the braking block 22 is located between the housing 10 and the first lateral plate 122. When the braking plate 20 rotates, the braking block 22 would be thrown out from a closed position to an expanding position by centrifugal force to abut against the stopping block 122a and thereby to restrict the rotation of the rotation unit 14.
Referring to FIG. 2, if the worker falls accidentally from the elevated workplace, the braking block 22 would pivotally swing to the expanding position to abut against the stopping block 122a on the first lateral plate 122 via a stopping part 222 formed thereon under normal condition, thereby enabling an immediate brake to stop the rotation of the rotation unit 14 so as to prevent the worker from continuing to fall.
Though, the fall protection devices 1 are usually used in dusty environments such that a pivoted portion of the braking block 22 is probably adhered by dust which makes the braking block 22 be stuck with the pivot 202a. Dust adhesions on the pivoted portion of the braking block 22 may cause the braking block 22 to be unable to be thrown out in emergency situations, resulting the lockup function to fail. Therefore, the pivoted portion between the braking block 22 and the braking plate 20 could be designed to have a loose fit to prevent the braking block 22 from being stuck by dust particles.
However, the loose-fit design would have a possibility that the braking block 22 swings toward a direction away from the exterior surface 202 of the braking plate 20 (as shown in FIG. 3). Especially if assembling tolerances resulting an interval between the housing 10 and the exterior surface 202 of the braking plate 20 become too large, it is possible that the stopping part 222 of the braking block 22 would not be stopped by the stopping block 122a and the lockup function fails.